A Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA) system adopts a Common Pilot Channel (Common Pilot Channel, CPICH) signal to perform channel estimation. During the channel estimation, a smoothing process is generally required to eliminate the influence of interferences such as noises. The principle of determining a smooth window length is that the smooth window length is as long as possible while ensuring correlation between signals within the window. If the smooth window length is too small, the correlation between signals cannot be fully utilized, so that a good noise suppression effect is unable to be achieved. If the smooth window length is too large, the smoothing operation is performed on signals with low correlation, so that the accuracy of channel estimation is decreased and throughput performance is directly affected. Therefore, proper selection of the smooth window length according to the signal correlation is one of the efficient ways to increase the accuracy of the channel estimation and improve system performance.
In wireless communications, the signal correlation may be measured by a coherence time, which is a statistical average value of time intervals in which a channel impulse response remains the same, and is approximately the reciprocal of a Doppler frequency shift. The Doppler frequency shift is mainly caused by a relative speed between a user device and a base station. The smooth window lengths in optimal channel estimation corresponding to different speeds are different.
In the prior art, a fixed smooth window length is adopted during determination of the smooth window length, which may cause that the suppression performance gain cannot be obtained at a low speed and that the data having relatively low correlation may be introduced at a high speed, thereby causing the performance degradation.